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West Epoxy

I read that 205 resin turns amber once exposed to oxygen, so some choose 206. Which hardner do you use?

Do you guys use thickner when using epoxy? Is it necessary? If so, why?

How about additives such as microfibers or similar?

Lastly, I've read on archive that some epoxy softens at temp around 130'F. I'm thinking this will not be a good situations in places like Arizona where temp on a hot summer gets clost to that...right? I'm talking if you were to laminate your neck using epoxy.

Thanks guys! David-

David buddy I am not sure for which application you are asking about West Systems for.

For pore filling I use 105/205 with no thickener. Epoxy in general is UV sensitive and may amber a bit with UV exposure. But you can also just fill the pores and sand back to the wood too eliminating this from happening IF you don't like the slight amber/vintage color that may result.

For structural applications like laminating necks the boat builder guys tell me to wet each side of the wood and then use a layer with some filler in the middle. I don't think that your glue lines are going to show which is what is throwing me off about your concern about an amber tint.

For things like fret boards where the glue joint is not going to be stressed I use West 105/205 wetting both sides and no filler layer. No problems so far.

As for a 130 softening temp I can't imagine wanting to expose a guitar to these temps anyway. HHG will be softening at these temps too.

Hi Hesh,

Do you have to wet both surface? or is that something you just do? or why do you do that?

thanks, David

Hey David!

You want to wet both surfaces so as to give the epoxy the best chance at bonding and penetrating everything. I thought that this was an odd application method too but that is how these guys told me to do it too. Sorry I don't have a better answer but I am sure someone will weigh-in here with one.

See my thread regarding squeeze-out. Mask off the fret side to minimize clean up later. I just buttered up the neck and the fingerboard and sandwiched the two together. There was plenty of squeeze-out all around.

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Christian

The hardeners do amber after they're open and are exposed to oxygen. Gougeon Brothers claim it is only aesthetic and does not effect performance. I use 205. I buy quarts instead of gallons, so go through it fast enough to not worry about it much, but I do keep a few single-use sealed packs around for cases where the color may matter. You could probably use something like Bloxygen to preserve the hardener color once the can is opened.

I do add fillers like the microfibers on any structural bonding, especially on heavily porous or softer woods. Check the Gougeon web site and literature. They have an awful lot of good information and tips available.

And it does weaken at a relatively low temperature - probably about the same as PVA glues, or around 140f to the best of my knowledge. That's why I put a big sticker that says "DO NOT TO EXPOSE TO EXTREME HEAT, HUMIDITY, OR DRYNESS" on the top of every guitar that comes through my shop. Just trying to save people from their own stupidity - I consider it a public service.

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Eschew obfuscation, espouse elucidation.

I've gone through gallons and gallons of epoxy. A number of time I buy the 5 gal. pail.

The major failure elements for people using epoxy are:

-poor mix, ratio and stirring.
-improper application.
-excessive squeeze-out.

Epoxy is a two part chemical mix. Therefore it is critical that the two parts be mixed in the correct ratio, and mixed well to ensure that all the mixture has been combined equally.

The epoxy will wick into the wood fiber. You need to ensure that there is epoxy in between the two pieces of wood that you will be bonding. That is why you prime the wood surfaces first, you want to keep a wet look prior to sticking the two pieces together.

If you do not have enough epoxy coating the mating surfaces, or you over clamp the joint squeezing out too much epoxy, you will starve the glue joint. While it may seem to be bonded, only a certain percentage of the surfaces will actually be bonding. This is one reason, actually the primary reason, why you use a filler in the epoxy when bonding, it ensure more contact and makes it harder to accomplish excessive squeeze out. There are a variety of fillers. The most common for structural bonding are silica and cotton fiber. Wood flour from your sander is also excellent.

Yes, the hardener does take on an amber tint when its exposed to oxygen. The extent of it depends upon how full your container is. A little hardener in a big can/jar exposed for a longer time will take on more colour. Remember, the epoxy is still used 1 part hardener to 5 parts resin, so the intensity of colour in your mix is small. Even when used as a film coating, it is pretty much overwhelmed by the wood colour anyway, you'd be hard pressed to account for any colour in the result as due solely to the epoxy. In a glue joint, the colour should be a non issue. There will be a greater impact from having any epoxy glue line there at all, than can be attributed to the tint of the epoxy.

Speaking of glue lines, I have sometimes used this to effect by really adding some colour. Adding red (or other colour) resin pigment in a stack of pale wood laminates can have a striking effect. I will play with that again when opportunity strikes.

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Actually, I think that HHG has a rather high tolerence to heat....at least until moisture is added. But HHG is one of the most heat resistant glues we use. I am thinking like upwards of 500 degrees but it may be like 300 degrees. I can look it up again though, but in any regard it is better than twice as heat tolerant when compared to most others. But the wood in a guitar (the joints mostly) is not going to fair very well if left much over 100 degress for too long!

Shane

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